Rear shock rattling noise

So I have a rattling noise coming from the rear shock on the driver's side. When you wiggle the plastic shock boot you can hear what sounds like a thin piece of metal rattling, so I hear this almost all the time on roads that are even a little bit bumpy. The other side doesn't have this noise, you can wiggle the shock boot but no metal rattling. Yesterday I had the back end of the car up on jack stands with the wheel off looking for any loose parts but didn't find any. Also the rattling noise is gone with the car lifted up and the wheel off.

Anyone else seen this before on your 5? Could it be something loose or broken inside the shock? I could replace the rear shocks if I had to, even though they don't leak and they're the originals with only 53000 miles on them. They are a bit bouncy when I do the "bounce test" on the back bumper but not too bad. I also seem to notice the back end of the car sways side to side a bit going over big bumps at higher speed.

One more bit of info, the shock with the noise has some vertical scratch marks on it that go right down to the bare metal. The other side looks like it has the same scratches but they're very faint. I have a picture in my phone and I can try to get it posted on here for anyone who wants to see it.

And as always needs to be said... don't replace with OEM mazda shocks, they'll just blow again very quickly, get something aftermarket. Cheap and reliable are the KYB's or Munroe's. But if you're looking for more performance, tuning, etc... there are lots of options out there... and more expensive.

I replaced my shocks/struts (Sensen struts) but still have that same rattling sound the OP has... and I still can't find it... Everything feels/looks tight when off the ground (looking at suspension bushings, etc).

I just replaced mine 3 days ago at 58K miles. The left one (rear) was leaking bad. Easy job to do and it does help to have an impact wrench, but not necessary if you have strong hands. Cost me $78 at autozone for the pair.

So I have a rattling noise coming from the rear shock on the driver's side. When you wiggle the plastic shock boot you can hear what sounds like a thin piece of metal rattling, so I hear this almost all the time on roads that are even a little bit bumpy. The other side doesn't have this noise, you can wiggle the shock boot but no metal rattling. Yesterday I had the back end of the car up on jack stands with the wheel off looking for any loose parts but didn't find any. Also the rattling noise is gone with the car lifted up and the wheel off.

Anyone else seen this before on your 5? Could it be something loose or broken inside the shock? I could replace the rear shocks if I had to, even though they don't leak and they're the originals with only 53000 miles on them. They are a bit bouncy when I do the "bounce test" on the back bumper but not too bad. I also seem to notice the back end of the car sways side to side a bit going over big bumps at higher speed.

One more bit of info, the shock with the noise has some vertical scratch marks on it that go right down to the bare metal. The other side looks like it has the same scratches but they're very faint. I have a picture in my phone and I can try to get it posted on here for anyone who wants to see it.

Any ideas/suggestions are welcome. Thanks!

Do you have any play between the shock and the "ears" of the mount at the bottom? I've heard of people hearing noise because of the shock shifting back and forth on the bolt.